Sometimes I'll use one if it's someone I don't talk to regularly, but if it's someone I know I don't. I have a similar policy with endings. If I'm asking for something, I'll use "thanks" because it seems polite. If I'm apologizing or being formal in some way, I'll often use "sincerely" or something similar.
Otherwise, what I do depends on how often I email them and how well they know me. If they don't know me or I don't often email them, then I'll close with just a dash and my name, in order to make it clear who I am and build an association. If they already know me well and we email fairly regularly, I won't use my name ("Thanks-\nJeb" becomes "Thanks!"), because it just adds noise.
Otherwise, what I do depends on how often I email them and how well they know me. If they don't know me or I don't often email them, then I'll close with just a dash and my name, in order to make it clear who I am and build an association. If they already know me well and we email fairly regularly, I won't use my name ("Thanks-\nJeb" becomes "Thanks!"), because it just adds noise.
(These aren't hard rules, of course.)